Sound amplifier for phonographs and method of making the same



c. 1. DODGE. y SOUND AMPLIFIER FOR PHON'OGRAPHS AND METHOD 0F MAKING THE SAME.

' APPLICATION FILED DEC. 6. 1918. 429,937, Patent@ sem. 26,1922.

2 SHEETS-SHEET l.

ATTORN EY 0.1. DODGE.' SOUND AMPLIFIER FOR PHONOGRAPHS AND METHOD 0F MAKING THE SA Patented Sept. 26, 71922.

APPLICATION FILED DEC.6. 1918.

2 SHEETSSHEET 2.

ATTORN EY I utilize libre to strengthen the material and wood tibi-e.

for acoustical A convenient f paper with reduce the whole to is sti'ained or presse reasons I prefer to use way of preparuce paper made of wood pulp by boiling a quanjust sufficient water to a soft mass. d to remove the greater portion of the water.

The sawdust is prepared by mixing it with the raw linseed oil.

that would tend properties of the l e whiting is to reduce the acoustical' sawdust.

added tothe mixture of sawdust and oil and the whole is thoroughly mixed.

The glue is made off to about the consistency of cabinet makers glue and one half the quantity is In comprises the saw bre or wood pulp is also added.

thus made is tl time for handling with the mass which oil and Whiting. The The mass ixe'd dust,

ien kneaded like dough. It will not set quickly so that there is ample the material and working it into the proper condition, which should be as tree holes. lVhen the above mass is the plastei' of hall of the glue. tendency last operation is t material is used.

should have about or putty. lt is plastic condition iii order that the to make as possible from bubbles or air material is to be used the pared by kneading into it )rc ljaris and the remaining one- The plaster of Paris has a the mass set so that this -arried out just before the The mass thus prepared the consistency of dough preferable to maintain a, through the various steps sawdust and fibre will remain evenly distributed throughout the mass. The mass last described as shown in Figure 10 back and forth o out into a body of even move air spaces. to be applied to astie material i mould or form tact throughout,

being pressed together seam. It is pref has been applied Figures 4 and 5 ing air 'holes and the material smo ness. lt' desired, tore the material latter trom adlier lett on the form set and then th removed.

It will be obser to pass the ro portions thereof tor the purpose of clim' until it has pa is then rolled out by passinga roller e mass to flatten it thickness and to re- The material is then ready the form. The sheet ot s then placed around the ver th and pressed into close conthe edges or' the material t there is no the material shown in erable, after to the form toi' the purpose of getting may be oiled beto prevent the The material is rtly or wholly form is` disassembled and is applic( ing to it.

ved that the throat l and i the horn 2 are made in one homogeneous body without joints and the density of the whole can be very uniform. This renders the amplifier very satisfactory for phonographs as it is clear in tone. The sawdust and libre make it possible to amplify the tones with all their quality as these elements have similar characteristic acoustical properties as the libre construction in wooden At the same time, there is no regular arrangement of these elements coi'- responding to the grain of natural wood and l consider this an advantage because, where the amplifier comprises a curved portion like the throat 1 a natural grain structure can not be advantageously arranged for all p0rtions of the curved body.

By making the amplilier ot' plastic material it is an easy matter to eliminate objectionable angles and to pass gradually from a round into a substantially rectangular body. In Figures 1, 2 and il l have shown an amplifier which has a circular cross section, as shown in Figure 2. t'roin the end 3 of the throat down to about the line et. The body then grzulually'tapers into a substan tiall rectangular formation. As shown in Fieure 3 the four sides have a slieht curve n 9 b or swell at 5 and at the meeting lines tue body has curves 6 oit' even thickness.

elimination ot sharp corners is'better vfor amplier is const In the draw The top of the member 7 tends to a line which is sligl axial line ot' the perpendicular portion l() of the throat. At the back there is a key 1l projecting upwardly from the top 12 and at the fronttliere is a socket 13 extending inwardly Jfrom the flattened portion 14. At the bottom the socket 13 has an undercut 15 in which another form member is adapted to lock.

'lhe member 1G which Forms the part of the mould, near the inner side of the throat bend is shown in Figure 8. lt consists ot' a block having a projection 17 which is slightly tapering to permit its disengagement and this member fits snugly into the socket 13. rlhis member 17 tapers narrmver from front to rear as shown and it tapers narrower from the top toward the bottom, so that it Will fit preferably en` itly below the lll The remaining member of tbe form is the, one over which the upright portion of the tbroet is formed. This member 22, is preierably cilindrica-l for the greater part of its lengte und it hes its roer end curved at 23 to form e. continuation of the curve of the member i'. lt also is out away to e linev belouT the exis, to form a fist portion 24 which is adapted to rest against the tops of the :members 16 end 7. This member 22 bes e recess 25 et its rear end to receive the key 1l of the member 'I and it bas a recess 26 to receive the key 21 of the member 16, the purpose of these lreys being 'to keep the form members in alignment.

When the several form members are asu sembled, es. shown in Figures Il and 5, their combined contours conform to the shape or' the interior of tile amplifier, with no -pro jections or shoulders to interlock with the .moulding materiel. l have shown a simple errengement for holding the form members together while the amplifier is being formed, and which will permit of ready disassembling,y of the form. There is e bar 27 er'- ranged across the member 22 und one end of a rope 28 is fastened to this bar. The rope passes through the bore 2g oi .the member 22 through the cutaway 30 of the member 16 und through the interior of tbe member 7 end its other end is fastened to e cross ber Elin tbe member 7. 'llie letter bar is accessible through en opening 32 in tbe base end the tray. When the rope 28 is tightened und secured in the manner shown it draws tbe several forno members 'together et their meeting surfaces und holds them rmly in that condition.Y

The member 7 is preferably attecbed to e. tray 33 heving the flange 34 extending around its edge. This fienge may serve es e guide to gouge the thickness of the meteriel applied to the ormend there is a cop 35 heving o. flange 36 spaced from tbe member 22 to gauge the thickness of the materiel et tbe upper end of the form.

The form is assembled as shown in Figures end 5 when e cest is to be mede. The materiel is then applied over the Whole er.- terior of the form and then pressed or rolled even und uniform in thickness and the maf textiel is then allowed to set While still on the form. The material may remain on the form until it has completely set and ban'` deneol or it may even be removed before it' has entirely set but after it has dried out suciently to maintain its shape until completely dried. When the material has sulli ciently set to permit'the removal of the form the rope 28 is released from the bar 3l and the several form members ere then no longer held together. The form member` 7 may be Withdrawn from the larger end of the amplifier, as the parts of the form are so designed that the member 7 Will disengege from the members 22, 16 when the member 7 is drawn downwardly or out through the larger end of lthe' amplifier. T he form member 22 may now be Withdrawn endwise from the tubular portion 10 of the throat und in a direction at right angle to the movement of the larger form member 7. The engagement between the members 22 and 16 is such that the former may be withdrawn endwise in the manner described. When both members 22 and 7 have been thus withdrawn, the member 16 which occupied the inner side of the bend of the throat will drop out because there is then nothing to maintain it in position. In this manner the form is disassembled and removed from the amplifier Without injuring or distorting the latter and the form is adapted to be used over und over again.

l have 'found that the shape or the empliA lier shown herein is a decided improvement over others having rectangular cross sections and that l obtain clearer and more brilliant reproductions with it. l shall, therefore,

claim herein en amplifier having the shape l. An amplifier for phonogrephs heifn a. n

tapering sound chamber end composed or a. composition of metter consisting principally oi plaster and having Wood fibre incorpo 'rated in and intimately ruined therewith to form e homogeneous mess. I

2. An amplifier for phonogrephs havin-g a tapering sound chamber und composed fof e. mouldable composition of\.ma.tter consisting principally of plaster and having Jood libre und sawdust incorporated in and inti mately mixed therewith to orrn s homogeneous mass.

3. An amplifier for phonogrephs baring o. tapering sound chamber and composed of e mouldeblecomposition of matter which includes plaster of Peris, Whiting; glue sind buying wood bre incorporated in sind intimately mixed therewith to form e homowhich includes plaster of Peris, Whiting,

glue and linseed oil and having wood fibre isb ' mcorpomtd eid intimately mixed there with-to form e, homogeneous mass.

5, A sound amper having n--taperng sound chamber and composed of a. mouldaole materiel including in its New York, 

